I think my Sennheiser PMX-100 (street style band) work very well with the Tomahawk, and tied for synergy is my SE530.

My next choice being my Grado SR-60 and iGrado. In the IEM world, the JVC marshmallows with the Kramer mod also seem to be a good match, but the JVC FX66 air cushion get increased sibilance with the Tomahawk, as do my Denon C700 - neither is a good match.

I haven't tried the Koss KSC-75 yet, I really need to tear into the box, and will likely do that when the KSC-35 show up next week.